Joining two gas supply lines

[Peter Nielsen]

I am new to this forum, so please be patient as I learn the protocols. I have several properties and do remodels. The plumbing subcontractor I have been using did something I have not seen before. There are two natural gas supply lines coming into a building which were installed at different times, the second one when a snow melt system was installed. We are now adding a small apartment in a previously unused attic area. Neither supply line has enough capacity to add the gas appliances, but together there is more than enough capacity. The subcontractor joined the two supply lines together and then connected a manifold to run to the new appliances. Drawings and calculations were submitted to the city showing the capacities and loads and approved. But, I'm not sure the city paid close attention to what was proposed in the drawings. Is there any prohibition in the building codes for joining two supply lines in this manner? Thanks for your input.

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[Jerry Peck]

IF ... IF BOTH gas supply lines were manifolded together at the SUPPLY CONNECTION and run through ONE VALVE which shut BOTH OFF , then it might be okay.

That would not be any different than coming in from one supply, having one shut off valve, then manifolding out to appliances.

[THOMAS HORNE]

IF ... IF BOTH gas supply lines were manifolded together at the SUPPLY CONNECTION and run through ONE VALVE which shut BOTH OFF , then it might be okay.

That would not be any different than coming in from one supply, having one shut off valve, then manifolding out to appliances.

This really is a question rather than an attempted gotcha. I simply do not know and I would like to learn. Doesn't the fuel gas code require that a building have a single shut off ahead of any individual shut offs such as those for apartments. It has been a long time since my Fire Protection courses in college and not that much more recently when I last had an in service training or training academy class on the fuel gas code. I just don't remember if the Fuel Gas Code requires a single shut off or not.

Whether or not the code allows it my firefighters instinct tells me that this is a bad thing! If the firefighter riding the utility control position on the truck company makes a mistake because of the second shut off any of the attack or search crews could be exposed to a large flow of burning natural gas when the still pressurized line cooks off.

The Service Standard of the supplying utility is just as important as the Fuel Gas Code. They have a right to deprive a dangerous installation of service. If one of the meter readers doesn't like the look of the arrangement and calls in a trouble crew you could find the gas shut off at a very inconvenient time. No turn on would then occur until a licensed gas fitter corrects the problem and obtains an accepted inspection or the Utility charges you for the needed correction. If the 2 gas lines were joined on the inside of the building out of the meter reader's sight then you will get away with it until it causes someone harm. I really do hope that the single valve referred to must be outside the building and control the entire Fuel Gas supply to the building.

--
Tom Horne

[Jerry Peck]

From the IRC: (bold and underlining are mine)

- Service shutoff. A valve, installed by the serving gas supplier between the service meter or source of supply and the customer piping system, to shut off the entire piping system.


- Point Of Delivery. For natural gas systems, the point of delivery is the outlet of the service meter assembly or the outlet of the service regulator or service shutoff valve where a meter is not provided. Where a valve is provided at the outlet of the service meter assembly, such valve shall be considered to be downstream of the point of delivery. For undiluted liquefied petroleum gas systems, the point of delivery shall be considered to be the outlet of the service pressure regulator, exclusive of line gas regulator, in the system.


- G2412.1.1 (401.1.1) Utility piping systems located within buildings.
- - Utility service piping located within buildings shall be installed in accordance with the structural safety and fire protection provisions of this code.


- Piping System. The fuel piping, valves and fittings from the outlet of the point of delivery to the outlets of the appliance shutoff valves.


- G2420.1 (409.1) General.
- - Piping systems shall be provided with shutoff valves in accordance with this section.


- G2420.2 (409.2) Meter valve.
- - Every meter shall be equipped with a shutoff valve located on the supply side of the meter.


- G2420.3 (409.3.2) Individual buildings.
- - In a common system service more than one building, shutoff valves shall be installed outdoors at each building.

I didn't specifically find where the service shutoff valve is required "outside" the building for individual buildings on an individual system. Nor where the meter is required to be outside the buildings (hopefully I just missed it, but my recollection from years ago is that meters are allowed inside buildings, and the "shutoff valve located on the supply side of the meter").

In fact, there are sections which state that such is allowed "Utility service piping located within buildings", but there is no definition for "utility service piping", however, presumably, that would be on the utility service side of the shutoff valve.

One item is the definition of "Service shutoff valve":
"A valve, installed by the serving gas supplier between the service meter or source of supply and the customer piping system ... "

"A valve" = singular

And the location for that valve is specified "between the service meter or source of supply and the customer piping system", but it does not state 'outside the building'.

Thus, as I said:

IF ... IF BOTH gas supply lines were manifolded together at the SUPPLY CONNECTION and run through ONE VALVE which shut BOTH OFF , then it might be okay.